"I believe that by definition if you believe it is better that your laws are decided somewhere else and that the Supreme Court of your land rests in a foreign city you are not patriotic.

"The primary identity of anyone who believes the EU flag is a good idea and stands ramrod to attention when the European anthem is played is European, not British." Who will win in tonight's debate?

The debate, which is being hosted by LBC radio, is likely to fuel calls for Mr Farage to take part in the leaders' debates ahead of the 2015 election. Mr Cameron's senior advisers are said to be against Mr Farage taking part.

Mr Farage said he is "confident" in the strength of his arguments and does not want the debate to descend into a "personal slagging match".

He said: "Am I delighted that an issue swept under the carpet for decades is going to be discussed publicly? Yes I am.

"I don't underestimate Nick Clegg, he is a guy of remarkable achievement. It is the first time the Lib Dems have been in Coalition since the war and I don't underestimate him at all.

"But am I confident of my arguments, and do I think that increasingly a clear, coherent case that Britain is outside the EU is winning supporters? Yes. Let's hope it [the debate] is fun too."

The debate will be hosted by Nick Ferrari, the LBC presenter, and the decision about who speaks first will be determined by the flip of a euro coin.

Mr Clegg is not expected to respond directly to any personal comments directed at him by Mr Farage. He will argue that staying in the European Union is better for the economy, security and the environment.